i've got a 79 350 w/ a 600cfm holley 4bbl with a holley contender intake and 305 heads that were setup for smog w/ a stock cam. i have no smog equipment on the car. i also have a set of 4 to 1 headers that go into 2.5" pipe all the way back to the muffler. My question is how much of an increase in power can i expect if i would add a set of dart iron eagle heads with the 215cc fuel rail and the 2.05 intake valves also with a comp exteme energy cam that has these specs:

Cam Style Hydraulic flat tappet
Basic Operating RPM Range 2,300-6,500 RPM
Intake Duration 050 inch Lift 240
Exhaust Duration 050 inch Lift 246
Advertised Intake Duration 284
Advertised Exhaust Duration 296
Intake Valve Lift with Factory Rocker Arm Ratio 0.507
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.510
Lobe Separation (degrees) 110

I also want to change the intake but i'm not sure what to run any ideas would be helpfull. The carb i would be running is a holley 750 dp with mech secondaries. I would also like to run 1.5 full roller rockers. Also any ideas on how to make this set up more potent would be great. I also have a 125 shot of nitrous to through into the mix. The trans is a 700r4 w/ an aluminum driveshaft 2300 stall and a 3.23 posi rear. this will be on a car that does see some street use so it has to have some drivability.

Thanks Guys